some hollister stuff is nice. However, its too teenage-ish to me. I'd rather stand out than blend with the crowd.
I myself don't like wearing stuff where the logo is plastered on the shirt.
Teenage, young 20s, I recommend what most of the guys said. VERY nice jeans, FITTED clothing(shirts, jeans, etc.). Put some color too, but make sure it matches your skin tone. Don't go too crazy.
Get graphic tees, they are totally in. However, the designs on em shoudn't be too outstanding. No glitters, shiny stuff, skulls, birds(overdone IMO).
Get some crewnecks and vnecks. Get some accesorries(a necklace, rings, watch, etc.) Get a sports jacket too if you want.
Get some converse shoes..or diesal..or lacoste...
get shorts, the stylish ones you see at GAP or Old Navy. Start wearing linen pants since its summer...
I think if you get all that stuff, you are set.